Autologous bone marrow mononuclear cell implantation therapy is an effective limb salvage strategy for patients with severe peripheral arterial disease

Modalities to Deliver Cell Therapy for Treatment of Chronic Limb Threatening Ischemia

Significance: Chronic limb threatening ischemia (CLTI) is a severe form of peripheral arterial disease (PAD) that is associated with high rates of morbidity and mortality, and especially limb loss. In patients with no options for revascularization, stem cell therapy is a promising treatment option. Recent Advances: Cell therapy directly delivered to the affected ischemic limb has been shown to be a safe, effective, and feasible therapeutic alternative for patients with severe PAD. Multiple methods for cell delivery, including local, regional, and combination approaches, have been examined in both pre-clinical studies and clinical trials. This review focuses on delivery modalities used in clinical trials that deliver cell therapy to patients with severe PAD. Critical Issues: Patients with CLTI are at high risk for complications of the disease, such as amputations, leading to a poor quality of life. Many of these patients do not have viable options for revascularization using traditional interventional or surgical methods. Clinical trials have shown therapeutic benefit for cell therapy in these patients, but methods of cell treatment are not standardized, including the method of cell delivery to the ischemic limb. Future Directions: The ideal delivery approach for stem cell therapy in PAD patients remains unclear. Further studies are needed to determine the best modality of cell delivery to maximize clinical benefits.

Bioengineering Cell Therapy for Treatment of Peripheral Artery Disease

Peripheral artery disease is an atherosclerotic disease associated with limb ischemia that necessitates limb amputation in severe cases. Cell therapies comprised of adult mononuclear or stromal cells have been clinically tested and show moderate benefits. Bioengineering strategies can be applied to modify cell behavior and function in a controllable fashion. Using mechanically tunable or spatially controllable biomaterials, we highlight examples in which biomaterials can increase the survival and function of the transplanted cells to improve their revascularization efficacy in preclinical models. Biomaterials can be used in conjunction with soluble factors or genetic approaches to further modulate the behavior of transplanted cells and the locally implanted tissue environment in vivo. We critically assess the advances in bioengineering strategies such as 3-dimensional bioprinting and immunomodulatory biomaterials that can be applied to the treatment of peripheral artery disease and then discuss the current challenges and future directions in the implementation of bioengineering strategies.

The foot in diabetes - a reminder of an ever-present risk

The term 'diabetic foot disease' (DFD) often signifies the presence of foot ulceration and infection, but one must also be wary of the rarer occurrence of Charcot foot disease. The worldwide prevalence of DFD is 6.3% (95%CI: 5.4-7.3%). Foot complications present a major challenge to both patients and healthcare systems, with increased rates of hospitalisation and an almost trebled 5-year mortality. The Charcot foot often occurs in patients with long-standing diabetes, presenting as an inflamed or swollen foot or ankle, following unrecognised minor trauma. This review focuses on the prevention and early identification of the 'at-risk' foot. DFD is best managed by a multi-disciplinary foot clinic team consisting of podiatrists and healthcare professionals. This ensures a combination of expertise and provision of a multi-faceted evidence-based treatment plan. Current research using endothelial progenitor cells (EPC) and mesenchymal stem cells (MSC) offers a new dimension in wound management.

A regenerative approach to the pharmacological management of hard-to-heal wounds

A wound is considered hard-to-heal when, despite the appropriate clinical analysis and intervention, the wound area reduces by less than a third at four weeks and complete healing fails to occur within 12 weeks. The most prevalent hard-to-heal wounds are associated with underlying metabolic diseases or vascular insufficiency and include arterial, venous, pressure and diabetic foot ulcers. Their common features include an abnormal immune response and extended inflammatory phase, a subdued proliferation phase due to cellular insufficiencies and finally an almost non-existent remodeling phase. Advances in wound care technology, tested in both pre-clinical models and clinical trials, have paved the way for improved treatment options, focused on regeneration. These interventions have been shown to limit the extent of ongoing inflammatory damage, decrease bacterial load, promote angiogenesis and deposition of granulation tissue, and stimulate keratinocyte migration thereby promoting re-epithelialization in these wounds. The current review discusses these hard-to-heal wounds in the context of their underlying pathology and potential of advanced treatment options, which if applied promptly as a standard of care, could reduce morbidity, promote quality of life, and alleviate the burden on a strained health system.

SDF-1 secreted by mesenchymal stem cells promotes the migration of endothelial progenitor cells via CXCR4/PI3K/AKT pathway

Cell-based therapeutics bring great hope in areas of unmet medical needs. Mesenchymal stem cells (MSCs) have been suggested to facilitate neovascularization mainly by paracrine action. Endothelial progenitor cells (EPCs) can migrate to ischemic sites and participate in angiogenesis. The combination cell therapy that includes MSCs and EPCs has a favorable effect on ischemic limbs. However, the mechanism of combination cell therapy remains unclear. Herein, we investigate whether stromal cell-derived factor (SDF)-1 secreted by MSCs contributes to EPC migration to ischemic sites via CXCR4/Phosphoinositide 3-Kinases (PI3K)/protein kinase B (termed as AKT) signaling pathway. First, by a "dual-administration" approach, intramuscular MSC injections were supplemented with intravenous Qdot® 525 labeled-EPC injections in the mouse model of hind limb ischemia. Then, the mechanism of MSC effect on EPC migration was detected by the transwell system, tube-like structure formation assays, western blot assays in vitro. Results showed that the combination delivery of MSCs and EPCs enhanced the incorporation of EPCs into the vasculature and increased the capillary density in mouse ischemic hind limb. The numbers of CXCR4-positive EPCs increased after incubation with MSC-conditioned medium (CM). MSCs contributed to EPC migration and tube-like structure formation, both of which were suppressed by AMD3100 and wortmannin. Phospho-AKT induced by MSC-CM was attenuated when EPCs were pretreated with AMD3100 and wortmannin. In conclusion, we confirmed that MSCs contributes to EPC migration, which is mediated via CXCR4/PI3K/AKT signaling pathway.

Comprehensive Analysis of Cell Therapy on Chronic Skin Wound Healing: A Meta-Analysis

Wound healing has been greatly challenging in different acute and chronic skin injuries. Among them, nonrevascularizable critical limb ischemic ulcers, venous leg ulcers, and diabetic lower limb or extremity ulcers are well-known refractory skin injuries that are difficult to treat. Partly differentiated, progenitor cell-based graft transplantation or direct injection of autologous stem cells might promote the wound healing process. Studies aiming to comprehensively analyze the effects of cell therapy on skin wound healing could provide clinical evidence for skin injury treatment. Different databases were searched for full-text publications on the comparison between cell therapy and regular therapy. Heterogeneity was detected by the I² method, and a fixed effect model was applied for data pooling if heterogeneity was absent. Publication bias was analyzed using a funnel plot, and 10 studies were finally included in this study. After a long-term follow-up, fewer patients underwent major amputation in the cell therapy group, compared with the standard therapy group, and those in the cell therapy group were characterized by a smaller ulcer area. Moreover, there was a significant difference in the wound healing rate between the intervention and control groups. However, pain caused by skin wounds was hardly mitigated by cell therapy in patients with critical limb ischemia. In this study, cell therapy proved effective in decreasing the size of ulcers and improving the wound closure rate. Additionally, the major amputation rate was decreased in the cell therapy group. However, the symptoms of pain were hardly alleviated by cell therapy in patients with cutaneous ulcers caused by peripheral artery disease-related critical limb ischemia.

Treatment of chronic diabetic foot ulcers with adipose-derived stromal vascular fraction cell injections: Safety and evidence of efficacy at 1 year

Diabetes affects multiple systems in complex manners. Diabetic foot ulcers (DFUs) are a result of diabetes‐induced microarterial vessel disease and peripheral neuropathy. The presence of arteriosclerosis‐induced macroarterial disease can further complicate DFU pathophysiology. Recent studies suggest that mesenchymal stromal cell therapies can enhance tissue regeneration. This phase I study was designed to determine the safety and explore the efficacy of local injections of autologous adipose‐derived stromal vascular fraction (SVF) cells to treat nonhealing DFUs greater than 3 cm in diameter. Sixty‐three patients with type 2 diabetes with chronic DFU—all amputation candidates—were treated with 30 × 10⁶ SVF cells injected in the ulcer bed and periphery and along the pedal arteries. Patients were seen at 6 and 12 months to evaluate ulcer closure. Doppler ultrasounds were performed in a subset of subjects to determine vascular structural parameters. No intervention‐related serious adverse events were reported. At 6 months, 51 subjects had 100% DFU closure, and 8 subjects had ≥75% closure. Three subjects had early amputations, and one subject died. At 12 months, 50 subjects had 100% DFU healing and 4 subjects had ≥85% healing. Five subjects died between the 6‐ and 12‐month follow‐up visits. No deaths were intervention related. Doppler studies in 11 subjects revealed increases in peak systolic velocity and pulsatility index in 33 of 33 arteries, consistent with enhanced distal arterial runoff. These results indicate that SVF can be safely used to treat chronic DFU, with evidence of efficacy (wound healing) and mechanisms of action that include vascular repair and/or angiogenesis.

Adipose-derived stromal vascular fraction (SVF) cells for the treatment of non-reconstructable peripheral vascular disease in patients with critical limb ischemia: A 6-year follow-up showing durable effects

We previously reported 18-month results post-injection of adipose-derived stromal vascular fraction (SVF) cells in 10 patients with end-stage peripheral vascular disease (PVD) in critical limb ischemia (CLI) and candidates for amputation, secondary to long-standing diabetes and/or arteriosclerotic disease. We documented positive clinical outcomes demonstrating pain relief as a change in the Rutherford score, improvement of ankle-brachial ratios (ABI), complete healing of 6 critical-size ulcers and evidence of neovascularization to the foot by MRI-based angiography. We now report persistency of the effect 6 years post-procedure in five patients and 4 years post-procedure in four additional patients who remained asymptomatic until death due to cardiac causes (patient 3) and lost from the study (patient 1). The 10th patient died early in the study. All treated extremities remain asymptomatic with increased ambulation, no recurrence of ulceration, and doppler color flow imaging at various vascular levels of the extremity demonstrating persistent blood flow and the presence of pulses doppler waveforms in the treated foot. Despite the extent of the disease, the contralateral extremities have not worsened significantly and no new ulcerations have appeared in any of the patients. Collectively, these data demonstrate that SVF injections have a durable long-term benefit forestalling further progression of the disease.

Activity of the human immortalized endothelial progenitor cell line HEPC-CB.1 supporting in vitro angiogenesis

The human HEPC-CB.1 cell line with many characteristics of endothelial progenitor cells (EPC) was tested for its proangiogenic properties as a potentially therapeutic compound. HEPC-CB.1 cells’ potential to differentiate into endothelial cells was revealed after treating the cells with a mixture of ATRA, cAMP and VEGF, as shown by the reduced expression levels of CD133, CD271 and CD90 antigens, augmentation of CD146 and CD31, and a decrease in cell clonogenicity. The cooperation of HEPC-CB.1 with the endothelial cell line HSkMEC.2 resulted in the formation of a common network. Tube formation was significantly more effective when resulting from HEPC-CB.1 and HSkMEC.2 cell co-culture as compared to a monoculture of each cell line. The exocrine mechanism of HEPC-CB.1 and HSkMEC.2 cross talk by secreted factors was evidenced using the HEPC-CB.1 supernatant to increase the efficacy of HSkMEC.2 tube formation. The proangiogenic factors produced by HEPC-CB.1 were identified using cytokine antibody array. Out of 120 examined factors, the HEPC-CB.1 cell line produced 63, some with known angiogenic activity. As in vivo the angiogenic process occurs at low oxygen tension, it was observed that in hypoxia, the production of defined factors was augmented. The presented results demonstrate that HEPC-CB.1 cells are able to both cooperate and integrate in a newly formed network and produce factors that help the network formation. The results suggest that HEPC-CB.1 cells are indeed endothelial progenitors and may prove to be an effective tool in regenerative medicine.

Peripheral artery disease: the new frontiers of imaging techniques to evaluate the evolution of regenerative medicine

Introduction: Stem cells (ESC, iPSC, MSC) are known to have intrinsic regenerative properties. In the last decades numerous findings have favored the development of innovative therapeutic protocols based on the use of stem cells (Regenerative Medicine/Cell Therapy) for the treatment of numerous diseases including PAD, with promising results in preclinical studies. So far, several clinical studies have shown a general improvement of the patient's clinical outcome, however they possess many critical issues caused by the non-randomized design of the limited number of patients examined, the type cells to be used, their dosage, the short duration of treatment and also their delivery strategy. Areas covered: In this context, the use of the most advanced molecular imaging techniques will allow the visualization of very important physio-pathological processes otherwise invisible with conventional techniques, such as angiogenesis, also providing important structural and functional data. Expert opinion: The new frontier of cell therapy applied to PAD, potentially able to stop or even the process that causes the disease, with particular emphasis on the clinical aspects that different types of cells involve and on the use of more innovative molecular imaging techniques now available.

Biological therapies in otology

Hearing loss is present in millions of people worldwide. Current treatment for patients with severe to profound hearing loss consists of cochlear implantation. Providing the cochlear nerve is intact, patients generally benefit greatly from this intervention, frequently achieving significant improvements in speech comprehension. There are, however, some cases where current technology does not provide patients with adequate benefit. Ongoing research in cell transplantation and gene therapy promises to lead to new developments that will improve the function of cochlear implants. Translation of these experimental approaches is presently at an early stage. This review focuses on the application of biological therapies in severe hearing loss and discusses some of the barriers to translating basic scientific research into clinical reality. We emphasize the application of these novel therapies to cochlear implantation.

Mobile educational follow-up application for patients with peripheral arterial disease

OBJECTIVE

to describe the development of a prototype mobile educational application for nursing follow-up aimed at patients diagnosed with peripheral arterial disease.

METHOD

a prototype-based technological production study. The construction followed the contextualized instructional design model using two steps: analysis and design and development.

RESULTS

the pedagogical content of the application was based on a survey of needs of patients with Peripheral Arterial Disease and treatments recommended in the literature. The prototype developed contained concepts, risk factors, signs and symptoms, treatment, importance of medications and their side effects, frequent doubts, necessary health care, and follow-up of patients by monitoring the evolution of the cicatricial process of lesions and possible complications, clarification of doubts and stimulus for continuation of treatment.

CONCLUSION

the use of health applications is a technological tool with the potential to improve the follow-up of patients regarding the progress of the disease and self-care, monitoring of risk factors, co-participation of the patient in the treatment, family participation, as well as planning of individualized care, and cost reduction for the health system.

Stem/Progenitor Cells and Their Therapeutic Application in Cardiovascular Disease

Cardiovascular disease is the leading cause of death in the world. The stem/progenitor cell-based therapy has emerged as a promising approach for the treatment of a variety of cardiovascular diseases including myocardial infarction, stroke, peripheral arterial disease, and diabetes. An increasing number of evidence has shown that stem/progenitor cell transplantation could replenish damaged cells, improve cardiac and vascular functions, and repair injured tissues in many pre-clinical studies and clinical trials. In this review, we have outlined the major types of stem/progenitor cells, and summarized the studies in applying these cells, especially endothelial stem/progenitor cells and their derivatives, in the treatment of cardiovascular disease. Here the strategies used to improve the stem/progenitor cell-based therapies in cardiovascular disease and the challenges with these therapies in clinical applications are also reviewed.

Treatment of Arsenite Intoxication-Induced Peripheral Vasculopathy with Mesenchymal Stem Cells

Arsenite (As), a notorious toxic metal, is ubiquitously distributed in the earth and poses a serious threat to human health. Histopathological lesions of As intoxication are known as thromboangiitis obliterans, which are resistant to current treatment and often lead to lower limb amputation. In this study, we attempt to find that treatment with mesenchymal stem cells (MSCs) may be effective for As-induced vasculopathy. We first conducted an in vitro study with a co-culture system containing human MSCs and human umbilical vein endothelial cells (HUVECs) and treated individual and co-cultured cells with various concentrations of arsenite. We also designed an in vivo study in which Sprague Dawley (SD) rats received periodic intraperitoneal (IP) injections of 16 ppm arsenite for 12 weeks. MSCs were harvested from BALB/c mice that were transplanted via tail vein injection. We found that there was significantly higher cellular viability in human mesenchymal stem cells (hMSCs) than in HUVECs under concentrations of arsenite between 15 and 25 μM. The Annexin V apoptosis assay further confirmed this finding. Cytokine array assay for As-conditioned media revealed an elevated vascular endothelial growth factor (VEGF) level secreted by MSCs, which is crucial for HUVEC survival and was evaluated by an siRNA VEGF knockdown test. In the in vivo study, we demonstrated early apoptotic changes in the anterior tibial vessels of As-injected SD rats with a Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, but these apoptotic changes were less frequently observed upon MSCs transplantation, indicating that the cytoprotective effect of MSCs successfully protected against As-induced peripheral vasculopathy. The feasibility of MSCs to treat and /or prevent the progression of As-induced vasculopathy is justified. Further clinical studies are required to demonstrate the therapeutic efficacy of MSCs in patients suffering from As intoxication with vasculopathy.

Stem cell-based peripheral vascular regeneration

Chronic critical limb ischemia (CLI) represents an end-stage manifestation of peripheral arterial disease (PAD). CLI patients are at very high risk of amputation and cardiovascular complications, leading to severe morbidity and mortality. Because many patients with CLI are ineligible for conventional revascularization procedures, it is urgently needed to explore alternative strategies to improve blood supply in the ischemic tissue. Although researchers initially focused on gene/protein therapy using proangiogenic growth factors/cytokines, recent discovery of somatic stem/progenitor cells including bone marrow (BM)-derived endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) has drastically developed the field of therapeutic angiogenesis for CLI. Overall, early phase clinical trials demonstrated that stem/progenitor cell therapies may be safe, feasible and potentially effective. However, only few late-phase clinical trials have been conducted. This review provides an overview of the preclinical and clinical reports to demonstrate the usefulness and the current limitations of the cell-based therapies.

Endothelial and cardiac progenitor cells for cardiovascular repair: A controversial paradigm in cell therapy

Stem cells have the potential to differentiate into cardiovascular cell lineages and to stimulate tissue regeneration in a paracrine/autocrine manner; thus, they have been extensively studied as candidate cell sources for cardiovascular regeneration. Several preclinical and clinical studies addressing the therapeutic potential of endothelial progenitor cells (EPCs) and cardiac progenitor cells (CPCs) in cardiovascular diseases have been performed. For instance, autologous EPC transplantation and EPC mobilization through pharmacological agents contributed to vascular repair and neovascularization in different animal models of limb ischemia and myocardial infarction. Also, CPC administration and in situ stimulation of resident CPCs have been shown to improve myocardial survival and function in experimental models of ischemic heart disease. However, clinical studies using EPC- and CPC-based therapeutic approaches have produced mixed results. In this regard, intracoronary, intra-myocardial or intramuscular injection of either bone marrow-derived or peripheral blood progenitor cells has improved pathological features of tissue ischemia in humans, despite modest or no clinical benefit has been observed in most cases. Also, the intriguing scientific background surrounding the potential clinical applications of EPC capture stenting is still waiting for a confirmatory proof. Moreover, clinical findings on the efficacy of CPC-based cell therapy in heart diseases are still very preliminary and based on small-size studies. Despite promising evidence, widespread clinical application of both EPCs and CPCs remains delayed due to several unresolved issues. The present review provides a summary of the different applications of EPCs and CPCs for cardiovascular cell therapy and underlies their advantages and limitations.

Advances in translational inner ear stem cell research

Stem cell research is expanding our understanding of developmental biology as well as promising the development of new therapies for a range of different diseases. Within hearing research, the use of stem cells has focused mainly on cell replacement. Stem cells however have a broad range of other potential applications that are just beginning to be explored in the ear. Mesenchymal stem cells are an adult derived stem cell population that have been shown to produce growth factors, modulate the immune system and can differentiate into a wide variety of tissue types. Potential advantages of mesenchymal/adult stem cells are that they have no ethical constraints on their use. However, appropriate regulatory oversight seems necessary in order to protect patients from side effects. Disadvantages may be the lack of efficacy in many preclinical studies. But if proven safe and efficacious, they are easily translatable to clinical trials. The current review will focus on the potential application on mesenchymal stem cells for the treatment of inner ear disorders.

[Biological therapies in otology. German version]

Millions of people worldwide suffer from hearing loss. Current treatment for patients with severe to profound hearing loss consists of cochlear implants. Providing the cochlear nerve is intact, patients generally benefit enormously from this intervention, frequently achieving significant improvements in speech comprehension. There are, however, some cases where current technology does not provide patients with adequate benefit. New therapeutic concepts based on cell transplantation and gene therapy are developing rapidly, at least in the research sector. Compared to the wealth of basic research available in this area, translation of these new experimental approaches into clinical application is presently at a very early stage. The current review focuses on translatable treatment concepts and discusses the barriers that need to be overcome in order to translate basic scientific research into clinical reality. Furthermore, the first examples of clinical application of biological therapies in severe hearing loss are presented, particularly in connection with cochlear implants.

Concise Review: Endothelial Progenitor Cells in Regenerative Medicine: Applications and Challenges

Endothelial progenitor cells (EPCs) are currently being studied as candidate cell sources for revascularization strategies. Significant advances have been made in understanding the biology of EPCs, and preclinical studies have demonstrated the vasculogenic, angiogenic, and beneficial paracrine effects of transplanted EPCs in the treatment of ischemic diseases. Despite these promising results, widespread clinical acceptance of EPCs for clinical therapies remains hampered by several challenges. The present study provides a concise summary of the different EPC populations being studied for ischemic therapies and their known roles in the healing of ischemic tissues. The challenges and issues surrounding the use of EPCs and the current strategies being developed to improve the harvest efficiency and functionality of EPCs for application in regenerative medicine are discussed.

SIGNIFICANCE

Endothelial progenitor cells (EPCs) have immense clinical value for cardiovascular therapies. The present study provides a concise description of the EPC subpopulations being evaluated for clinical applications. The current major lines of investigation involving preclinical and clinical evaluations of EPCs are discussed, and significant gaps limiting the translation of EPCs are highlighted. The present report could be useful for clinicians and clinical researchers with interests in ischemic therapy and for basic scientists working in the related fields of tissue engineering and regenerative medicine.